Tesla releases software update to reduce charging speed, fire risk

Safety, one update at a time.

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In order to address the latest in a string of fires involving the battery-powered Model S, Tesla has quickly responded with a software update. Unlike the last several fires that stemmed from road accidents, this one happened in a garage in Irvine, California while the car was charging.

Investigators looking into the incident noted that the fire appears to have originated at a 240-volt wall charger rather than at the car, which sustained only minor smoke damage during the mid-November event.

While Tesla quickly disputed the cause, claiming its telemetry data showed the car was charging normally, the automaker has not been sitting idly by. As a Silicon Valley tech startup, Tesla Motors has clearly learned the lesson that if you're going to sell bleeding edge technology that occasionally doesn't perform as expected, you'll need to respond quickly to any problems that could affect your reputation.

Ryan Block, vice president of Product at AOL and a Model S owner, posted on an Engadget discussion forum that his car received an over-the-air firmware update this week that affects the charging control. According to the message he found on the 17-inch center console display this week, the update includes an automatic charge rate reduction.

The standard Tesla high-power wall connector for the Model S supplies 240 volts at 40 or 80 amps depending on whether the car is equipped with single or twin on-board chargers. The car's software will now more closely monitor the power delivery from the wall and automatically reduce the charging rate by 25 percent if it detects unexpected fluctuations. The intent is to detect and reduce the load if there are problems that could be caused by faults in the home wiring.

The takeaway here is that electric vehicles put a lot of additional load on a home's wiring. Anyone planning to own an electric vehicle should hire a good electrician before bringing the car home and make sure the wiring is up to snuff before plugging in for the first time.